SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a3974b9e7c6fe4f8d7af4e9bf5202f51d60c07be1f097873320bd16fc121674' 
  AND token = 'MXa3Vjs1ui5ncKnvGGcNZtlGDu6olq9/PAlZHqZLg0A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}